Implement generic mechanism to store flags (like deadline-notification-sent) on model record.
Idea
In some case we have to be able to store dynamic information on record. For exmaple, if we have sent notification about deadline, or if if was checked by some scheduler, etc.
For this reason we could implement new module, similar to tags, but for technical purposes. The reason, why we need separate module/model for this while it is possible to store this info as regular fielsd on same model, is following. When we have only few flags on the model, then it is ok. But what if we need 50+ flags on the model? Add 50 fields?
Possibly, we could implement mechanis for this by using postgres json fields Possibly, implement it with prefetch disabled, because usually it will be thechnical field used by schedulers only.